I think the WA22 in balanced mode is definitely a step above the 6SE, as others have said. It feels much more expansive and almost 3 dimensional with premium tubes. Like I said in an earlier post, if music gives me goosebumps then I know I made the right decision.
If going unbalanced, 6SE is basically awesome. I didn't have a single complaint about it, I just wanted to go that next step up and had a specific need/purpose.